# Independent component analysis with nonnegative mixing matrix

In independent component(s?) analysis, I have the observed signal, $O$, the mixing matrix, $A$, and the source matrix, $S$, with $O ≈ AS$

I've found some literature on ICA with the sources assumed to be nonnegative, but haven't been able to find anything on ICA with the mixing matrix assumed nonnegative. Does anyone know of whether algorithms for this exist?